1. Field of the Invention
The present invention relates generally to medical methods, systems, and kits. More particularly, the present invention relates to methods and apparatus for effecting lung volume reduction by aspirating isolated segments of lung tissue.
Chronic obstructive pulmonary disease is a significant medical problem affecting 16 million people or about 6% of the U.S. population. Specific diseases in this group include chronic bronchitis, asthmatic bronchitis, and emphysema. While a number of therapeutic interventions are used and have been proposed, none are completely effective, and chronic obstructive pulmonary disease remains the fourth most common cause of death in the United States. Thus, improved and alternative treatments and therapies would be of significant benefit.
Of particular interest to the present invention, lung function in patients suffering from some forms of chronic obstructive pulmonary disease can be improved by reducing the effective lung volume, typically by resecting diseased portions of the lung. Resection of diseased portions of the lungs both promotes expansion of the non-diseased regions of the lung and decreases the portion of inhaled air which goes into the lungs but is unable to transfer oxygen to the blood. Lung reduction is conventionally performed in open chest or thoracoscopic procedures where the lung is resected, typically using stapling devices having integral cutting blades.
While effective in many cases, conventional lung reduction surgery is significantly traumatic to the patient, even when thoracoscopic procedures are employed. Such procedures often result in the unintentional removal of healthy lung tissue, and frequently leave perforations or other discontinuities in the lung which result in air leakage from the remaining lung. Even technically successful procedures can cause respiratory failure, pneumonia, and death. In addition, many older or compromised patients are not able to be candidates for these procedures. For these reasons, it would be desirable to provide improved methods, systems, and kits for performing lung volume reduction which overcome at least some of the shortcomings noted above.
2. Description of the Background Art
WO 99/01076 and corresponding U.S. Pat. No. 5,957,919 describes devices and methods for reducing the size of lung tissue by applying heat energy to shrink collagen in the tissue. In one embodiment, air may be removed from a bleb in the lung to reduce its size. Air passages to the bleb may then be sealed, e.g., by heating, to fix the size of the bleb. WO 98/48706 describes a plug-like device for placement in a lung air passage to isolate a region of lung tissue, where air is not removed from the tissue prior to plugging. WO 98/49191 describes the use of surfactants in lung lavage for treating respiratory distress syndrome. U.S. Pat. No. 5,925,060 may also be of interest.
Patents and applications relating to lung access, diagnosis, and treatment include U.S. Pat. Nos. 5,957,949; 5,840,064; 5,830,222; 5,752,921; 5,707,352; 5,682,880; 5,660,175; 5,653,231; 5,645,519; 5,642,730; 5,598,840; 5,499,625; 5,477,851; 5,361,753; 5,331,947; 5,309,903; 5,285,778; 5,146,916; 5,143,062; 5,056,529; 4,976,710; 4,955,375; 4,961,738; 4,958,932; 4,949,716; 4,896,941; 4,862,874; 4,850,371; 4,846,153; 4,819,664; 4,784,133; 4,742,819; 4,716,896; 4,567,882; 4,453,545; 4,468,216; 4,327,721; 4,327,720; 4,041,936; 3,913,568 3,866,599; 3,776,222; 3,677,262; 3,669,098; 3,542,026; 3,498,286; 3,322,126; WO 95/33506, and WO 92/10971.
Lung volume reduction surgery is described in many publications, including Becker et al. (1998) Am. J. Respir. Crit. Care Med. 157:1593-1599; Criner et al. (1998) Am. S. Respir. Crit. Care Med. 157:1578-1585; Kotloff et al. (1998) Chest 113:890-895; and Ojo et al. (1997) Chest 112:1494-1500.
The use of mucolytic agents for clearing lung obstructions is described in Sclafani (1999) AARC Times, January, 69-97. Use of a balloon-cuffed bronchofiberscope to reinflate a lung segment suffering from refractory atelectasis is described in Harada et al. (1983) Chest 84:725-728.
The present invention provides improved methods, systems, devices and kits for performing lung volume reduction in patients suffering from chronic obstructive pulmonary disease or other conditions where isolation of a lung segment or reduction of lung volume is desired. The present invention is likewise suitable for the treatment of bronchopleural fistula. The methods are minimally invasive with instruments being introduced through the mouth (endotracheally) and rely on isolating the target lung tissue segment from other regions of the lung. Isolation is achieved by deploying an obstructive device in a lung passageway leading to the target lung tissue segment. Once the obstructive device is anchored in place, the segment can be aspirated through the device. This may be achieved by a number of methods, including coupling an aspiration catheter to an inlet port on the obstruction device and aspirating through the port. Or, providing the port with a valve which allows outflow of gas from the isolated lung tissue segment during expiration of the respiratory cycle but prevents inflow of air during inspiration. In addition, a number of other methods may be used. The obstructive device may remain as an implant, to maintain isolation and optionally allow subsequent aspiration, or the device may be removed at any time. Likewise, the device may biodegrade over a period of time.
The obstruction device may take a variety of forms to allow delivery, deployment and anchoring in a lung passageway. Delivery is commonly performed with the use of a minimally invasive device, such as a flexible bronchoscope or an access catheter. The flexible bronchoscope may be utilized with a sheath having an inflatable cuff disposed near its distal end, a full description of which is provided in co-pending application Ser. No. 09/699,313, assigned to the assignee of the present invention and incorporated by reference for all purposes. When using such a sheath, the scope is introduced into a lumen in the sheath to form an assembly which is then introduced to the lung passageway. The cuff may then be inflated to occlude the passageway. Similarly, an access catheter may be used which may be steerable or articulating, may include an inflatable balloon cuff near its distal end and may include a number of lumens for balloon inflation, tracking over a guidewire, and optical imaging, to name a few. The obstruction device is typically housed within a lumen of the access catheter, bronchoscope, sheath or suitable device, mounted near the distal tip of the catheter or carried by any method to the desired lung passageway leading to the target lung tissue segment. Therefore, the obstruction device must be sized appropriately for such delivery and is typically designed to expand upon deployment to anchor within the lung passageway. Hereinafter the present invention is depicted in relation to use with an access catheter, however it may be appreciated that any suitable device may be used.
In a first aspect of the present invention, the obstruction device comprises a structural support which expands and thereby anchors the device in the lung passageway. Such supports may comprise a number of configurations for a variety of expansion techniques. For example, the structural supports may allow the obstruction device to coil, roll, bend, straighten or fold in a cone, rod, cylinder or other shape for delivery. Then, once positioned in a desired location, the obstruction device may be released and expanded to anchor the device in the passageway. Such expansion may be unaided, such as in the release of a compressed structure to a pre-formed expanded position. Or, such expansion may be aided, such as with the use of an inflatable balloon or cuff. In some cases, a balloon or inflatable member may be incorporated into the obstruction device and may remain inflated to occlude the passageway. This may be provided in combination with structural supports or an inflatable balloon or similar device may be used without such support.
The structural supports may be comprised of any type of wire, particularly superelastic, shape-memory or spring tempered wire, or any type of polymer or a suitable material. The balloon or inflatable member may be comprised of any flexible, polymeric material suitable for such a purpose. The member may be inflated with gas or liquid as desired, or it may be inflated with an expanding foam or similar material. Likewise, it may be inflated or injected with an adhesive. Such an adhesive may expand the member and/or rigidify the member to reduce the likelihood of collapse. Further, the adhesive may additionally serve to bond the device to the walls of the lung passageway to increase anchorage. In addition, the device may be impregnated or coated with an antibiotic agent, such as silver nitrate, or similar agent for delivery of the agent to the lung passageway. Such delivery may occur by any applicable means.
When structural supports are present, such supports may comprise a variety of designs. In a first embodiment, the structural supports comprise radial segments which expand to fill the passageway and longitudinal segments which rest against the walls of the passageway to help anchor the device. In a second embodiment, the structural supports comprise a mesh which expands to fill the passageway. In a third embodiment, the structural supports comprise a helically or spirally wound wire which also expands to contact the walls of the passageway and anchor the device. In each of these embodiments, the structural support may be connected with or encapsulated in a sack comprised of a thin polymeric film, open or closed cell foam or other suitable material to provide a seal against walls of the lung passageway and obstruct airflow through the device. The sack material may also be infused with an adhesive, sealant or other material to improve obstruction of the airway and possibly improve adhesion to the airway walls.
In a second aspect of the present invention, the obstruction device may further comprise ports for aspiration through the device. This may allow access to the collapsed lung segment at a later time, for example, in the case of an infection. Typically, the obstruction device will have an inlet port located near the proximal end of the device, away from the isolated lung tissue segment. Such a port is thus accessible by minimally invasive devices, such as an aspiration catheter, which may be advanced through the bronchial passageways. Optionally, an outlet port may be located near the distal end of the obstruction device. The ports may comprise a variety of designs for a number of purposes.
In a first embodiment, the port comprises a self-sealing septum. Such a septum may comprise a solid membrane or a pre-cut membrane. Aspiration through the port may be achieved with the use of an aspiration catheter having an access tube or penetrating element at its distal end. Such a catheter may be advanced to the site of the obstruction device itself or with the use of an access catheter. The septum may be penetrated, either pierced through a solid membrane or passed through the cuts of a pre-cut membrane, by the access tube. Depending on the design of the obstruction device, the inlet port and optionally the outlet port may be penetrated in this fashion. Aspiration may be achieved through the access tube and aspiration catheter to withdraw gases and/or liquids from the isolated lung tissue segment and passageway. Optionally, prior to aspiration, a 100% oxygen, Helium-Oxygen mixture or low molecular weight gas washout of the lung segment may be performed by introducing such gas through the access tube, such as by a high frequency jet ventilation process. In this case, aspiration would remove both the introduced gas and any remaining gas. Similarly, liquid perfluorocarbon or certain drugs, such as antibiotics, retinoic acid and hyaluronic acid, may be introduced prior to aspiration. In most cases, aspiration will at least partially collapse the lung segment. Upon removal of the aspiration catheter from the port, the septum may self-seal or it may be further sealed with a sealant or other sealing means for later access or permanent closure.
When the self-sealing septum comprises a pre-cut membrane, aspiration through the port may alternatively be achieved by coupling an aspiration catheter to the obstructive device. Coupling may comprise engaging the aspiration catheter to the port or sliding a coupling member or the aspiration catheter over the port to form a seal. In either case, suction through the aspiration catheter may allow gases and/or liquids to pass through the cuts in the membrane to be withdrawn from the isolated lung tissue segment and passageway. Again, this will at least partially collapse the lung segment. Likewise, upon removal of the aspiration catheter from the port, the septum may self-seal or it may be further sealed with a sealant or other sealing means for later access or permanent closure.
In a second embodiment, the port comprises a unidirectional valve. Such a valve may comprise a port covered by a flexible layer which is attached to the port by at least one point of connection. Movement of the layer away from the port opens the valve and movement against the port closes the valve. Wherein the flexible layer is solid, movement of the layer away from the port allows gas to flow between the points of connection and around the edges of the flexible layer. Alternatively, the flexible layer may have holes therethrough. In this case, the port may also comprise a partition having holes which are not aligned with the holes in the flexible layer. Movement of the layer away from the port allows gas to flow through the holes in the partition and out through the holes in the flexible layer. When the layer moves against the partition, the holes will be covered closing the valve. Other valve designs include a spring-loaded ball valve or a biased pre-loaded diaphragm valve.
Aspiration through a unidirectional valve may be achieved by a number of methods. Again, the port may be accessed by advancing an aspiration catheter or similar device through the bronchial passageways to the site of the obstruction device. This may optionally be achieved with the use of an access catheter. The aspiration catheter may be placed near the valve or engaged to the valve, wherein suction or vacuum applied through the catheter opens the valve. If the aspiration catheter is not engaged to the valve, adequate suction to open the valve may be achieved by occluding the passageway proximal to the point of suction which is typically the distal end of the aspiration catheter. Such occlusion may be achieved by inflating a balloon or occlusion device mounted on the distal end of the aspiration catheter or mounted on an access catheter. In either case, the vacuum may draw the flexible layer away from the port, allowing gases and/or liquids to flow out from the isolated lung segment, through the valve and into the aspiration catheter. Alternatively, aspiration through a unidirectional valve may be achieved naturally during respiration. Pressure changes may open the valve during expiration as gases flow out from the isolated lung segment. Reverse pressure changes, during inspiration, may close the valve preventing gases from flowing into the isolated segment. This may reduce the amount of gas trapped in the terminal segment over time and thus at least partially collapse the lung segment. Similarly, aspiration through the unidirectional valve may be achieved by external mechanical pressure on the lung to force out of the lung segment and through the valve. Again, reverse pressure changes upon recoil of the lung would close the valve preventing gases from flowing into the isolated segment.
In a third aspect of the present invention, the obstruction device may comprise a blockage device which is deployed in a lung passageway to close the airway. Such a blockage device may be of similar design as previously described obstruction devices as it may be similarly delivered, deployed and anchored within a lung passageway. Thus, embodiments of the blockage device typically comprise expandable support structures. For example, in one embodiment the support structure comprises a coil. And, in a second embodiment, the support structure comprises a mesh. Again, the support structures may be connected to or encased in a polymer film or sack to provide a seal against the walls of the lung passageway and obstruct airflow through the device. Typically the blockage device will be placed in the passageway after the terminal lung segment has been aspirated by other methods. This will seal off the lung segment and maintain lung volume reduction. Alternatively, the blockage device may be placed in the passageway before the terminal lung segment has been aspirated. In this case, air trapped in the lung segment may be absorbed over time and would eventually collapse, a process known as absorption atelectasis. This process may be enhanced by insufflating the lung segment with 100% oxygen, a Helium-Oxygen mixture or low molecular weight gas prior to placing the blockage device. Such enhancement may promote complete collapse of the lung segment. In any case, the blockage device may optionally be later removed if it is so desired.
Methods of the present invention include the utilization of an obstruction device to achieve lung volume reduction. As described above, methods include delivery, deployment and anchoring of an obstruction device in a lung passageway leading to a target lung tissue segment. At least partial collapse of the terminal lung tissue segment may be achieved by aspirating the segment through the obstruction device deployed in the passageway. Aspiration may be accomplished with the use of an aspiration catheter or similar device through a port on the obstruction device. Also described above, when the port comprises a unidirectional valve, aspiration and eventual lung volume reduction may be accomplished by the opening and closing of the valve in response the respiratory cycle. In addition, methods of the present invention include deployment of a blockage device in a lung passageway leading to a terminal lung tissue segment, as previously described.
Systems of the present invention may include any of the components described in relation to the present invention. A particular embodiment of a system of the present invention comprises an access catheter and an obstruction device, as described above, wherein the obstruction device is introduceable by the access catheter. For example, the obstruction device may be houseable within a lumen of the access catheter for deployment out the distal end of the catheter, or the obstruction device may be mountable on the access catheter near its distal end. In either case, the obstruction device may be deployed and anchored within a lung passageway.
The methods and apparatuses of the present invention may be provided in one or more kits for such use. The kits may comprise an obstruction device deployable within a lung passageway and instructions for use. Optionally, such kits may further include any of the other system components described in relation to the present invention and any other materials or items relevant to the present invention.
Other objects and advantages of the present invention will become apparent from the detailed description to follow, together with the accompanying drawings.